dmaengine: idxd: cleanup workqueue config after disabling

After disabling a device, we should clean up the internal state for
the wqs and zero out the configuration registers. Without doing so can cause
issues when the user reprogram the wqs.

Fixes: c52ca478

 ("dmaengine: idxd: add configuration component of driver")
Reported-by: Yixin Zhang <yixin.zhang@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Tested-by: Yixin Zhang <yixin.zhang@intel.com>
Link: https://lore.kernel.org/r/159311264246.1198.11955791213681679428.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>